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Noxious Neighbors: The EPA Knows Tanks Holding Heavy Fuels Emit Harmful Chemicals. Why Are Americans Still at Risk?

The agency has been aware for more than a decade that companies are underreporting emissions, using equations developed by the petroleum industry that are often wrong.

This article was produced in collaboration with Berkeley Journalism’s Investigative Reporting Program.

Brittany Liscord was at her job at the Children’s Museum & Theatre of Maine in 2018 when, out of nowhere, she received a warning from a colleague. It was about the massive petroleum storage tanks near her home.

“It came up that I was a runner in South Portland, and I guess he had done some work in another city that had tanks,” she said. “He said to me, ‘You should be really concerned about the VOCs in your area.’”

Liscord went home and Googled “VOCs,” while flashing back to a college introductory class on environmental science where the instructor had talked about the damage air pollutants could do to your lungs. She read that in significant amounts, VOCs—volatile organic compounds—could be highly dangerous to health. Now all she could think about was the smell outside her home, a noxious stench that on the worst days even made its way inside.

A company called Global Partners owned some of the tanks, which stood just a tenth of a mile from where she and her husband, Rob Liscord, lived, and held petroleum products, including asphalt and a heavy fuel oil known as No. 6. 

“I feel really fearful,” Rob Liscord said, adding that he gets headaches sometimes after he runs.

Rob and Brittany Liscord are photographed with their dog, Arlo, in their backyard in South Portland, Maine on Saturday, Feb. 13, 2021. The Liscords live one-tenth of a mile from storage tanks owned by Global Partners, an energy company that uses its tanks to store petroleum products. Global Partners and Sprague Resources, also located in South Portland, have settled lawsuits in recent years with the EPA for violating the Clean Air Act due to the high level of VOCs coming from their tanks. Credit: Yoon S. Byun
Rob and Brittany Liscord are photographed with their dog, Arlo, in their backyard in South Portland, Maine on Feb. 13. The Liscords live one-tenth of a mile from storage tanks owned by Global Partners, an energy company that uses its tanks to store petroleum products. Credit: Yoon S. Byun

On any given day, bulk storage tanks around the United States hold more than 2 billion gallons of asphalt or residual fuel, much of it No. 6, according to the Energy Information Administration. Some of the tanks sit at refineries, but a majority are located at terminals, known as tank farms, like the ones in the Liscord’s neighborhood in South Portland.

While emissions from petroleum products like gasoline or jet fuel have long been known to be dangerous and are subject to state and federal regulation, asphalt and No. 6 fuel oil, classified as “heavy refinery liquids,” have been largely ignored by regulators because it was thought that their emissions were negligible.

But in an 18-month investigation, Inside Climate News found that emissions from heated tanks containing asphalt and No. 6 fuel oil pose a risk to the health of millions of Americans who live close to the tanks, one that federal and state regulators have failed to adequately address. 

Changes in the petroleum refining process over the last 30 years have resulted in significant emissions from the two products when they are heated in tanks, as they must be to keep their contents in liquid form. And these emissions often contain VOCs that can pose a threat to human health, in some cases at levels high enough to violate federal clean air standards. The chemicals also combine with other pollutants to form ozone, a greenhouse gas that contributes to climate change.

In a few pockets around the United States, regulators have investigated VOC emissions from heated tanks, often finding them where they hadn’t expected to. Credit: Satellite image ©2021 Maxar Technologies

Yet companies that own the tanks have been routinely underreporting the extent of their emissions because instead of measuring the vapors from tanks, they estimate them using a set of equations developed by the petroleum industry and approved by the U.S. Environmental Protection Agency.

And those equations, it turns out, are often wrong.

Federal regulators and some industry insiders have known this for more than a decade, but have taken no action to mandate that companies report emissions or measure them directly. As a result, some states do not even require companies to track emissions from tanks containing asphalt or No. 6, and an overwhelming majority of states that do require it rely on the estimates from the petroleum industry equations. 

Only when Inside Climate News began asking questions about the chemicals in the fumes in South Portland did the tanks receive wider public attention. Since then, interviews with scientists, regulators, environmental advocates and government officials and documents obtained under the Freedom of Information Act have made clear the national scope of the problem. 

Some of the Health Risks from VOCs

Tank farms line waterways across the country, providing a critical stop in the distribution chain that brings the petroleum products to consumers. Owned by private companies like Global Partners, they are knit into communities, often just steps from neighborhoods, schools and playgrounds. In South Portland, the tanks sit near daycare centers and schools, retirement homes and working-class neighborhoods, like the one where the Liscords live.

Residents living near tanks that hold asphalt or No. 6 fuel oil have filed hundreds of complaints about noxious smells and reported symptoms—from headaches and breathing problems to cancers and other illnesses—that they worry might be connected to the tanks’ emissions. 

The EPA has been aware of the flawed industry formula at least since 2007, when Global Partners disclosed, as required by federal law, that it had found substantially higher than expected emissions from No. 6 fuel oil tanks.

In a 2007 letter to the EPA and to environmental regulators in Massachusetts, Global Partners, which owns 25 tank farms around the country, said that higher than expected emissions were not just the company’s problem. The higher emissions caused by the refining process changes and the inability of the formula to accurately predict emissions, the company wrote, were “an industry-wide issue.”

Global Partners’ letter set off an investigation by the EPA’s New England office into heated tanks owned by Global and other companies in the region, and eventually led to agreements with two companies, Global and Sprague Resources, to make changes to address the emissions problem in several cities in the region, including South Portland. 

But the EPA did not direct its field offices in other parts of the country to look into heated tanks in their regions. And though the agency advised that the estimates based on petroleum industry equations should only be used if direct measurements were unavailable, most companies and state regulators continue to rely on the estimates. 

Not until late last year did the EPA issue an enforcement alert about the unexpected emissions levels from heated tanks and the flaws in the formula when applied to these kinds of tanks, and the agency has taken no action since. 

Edward Braczyk, the northeast regional permit chief for the Massachusetts Department of Environmental Protection, which worked closely with the EPA on its regional investigation, said he had hoped that the agency would go on to take a far more aggressive, nationwide look at heated tank emissions. 

“It’s a shame,” said Braczyk. “We put all this effort in trying to push EPA to do more.”

The routine underestimation of emissions, some experts said, is not limited to heated tanks, but is a symptom of a much larger problem in which emissions from many petroleum sources are estimated rather than measured. Those estimates can be far off the mark, indicating much lower—or much higher—emissions than is actually the case. In a 2006 report, the Office of Inspector General of the EPA found that 62 percent of the equations used to calculate the estimates had been rated by the agency “below average” or “poor.”

“Everyone involved in the system has known about it. Has known the problems. Has known that shocking revelations are occurring,” said John Walke, the clean air director at the Natural Resources Defense Council. “And yet we continue to live with this broken system and accept these problems, these known deficiencies that are underreporting and under-controlling pollution.”

What is a Heated Tank?

Asphalt and No. 6 fuel oil are what is left once crude oil has been heated up and the high-value products like gasoline, jet fuel and diesel have been removed, leaving the thick sludge at the bottom of a vacuum stack. The sludge is so thick that it has to be heated to become liquid, requiring special tanks for storage. And it is so deeply-refined that more volatile products are added back into the tank to make the products useful. 

Noxious Neighbors

Inside a storage tank, asphalt is frequently heated to more than 300 degrees. No. 6 is often heated to 130 degrees. 

In South Portland, as in many ports, massive tanker ships arrive with their hulls filled with the products. Pipes carry the liquids from the ships to the tanks. The tanks—typically more than three stories high and 115 feet wide—then hold the product until it’s ready to move on to the next step in the supply chain by truck or train.

Historically, regulators assumed that asphalt and No. 6 fuel oil products did not produce  emissions of any significance, just because they were so thick and depleted. The EPA, which provides guidance to states on how to enforce the Clean Air Act, does not even include asphalt in its handbook for estimating emissions from petroleum tanks, although it does include No. 6. These assumptions have contributed to the impression in some states that asphalt and No. 6 oil do not need to be regulated, according to the heads of state air agencies.

“To our knowledge, the US EPA has not identified tanks storing these products as needing rules” under the Clean Air Act, Doug Carr, the chief of energy branch of the Alabama Department of Environmental Management air division, said. “Therefore, ADEM considers these tanks to be insignificant sources of air pollutants, and they are not required to hold permits under our permit program.”

But as refineries have gotten better at squeezing every valuable drop out of the more profitable materials higher up in the vacuum stack, the sludge at the bottom—what becomes No. 6 fuel or asphalt—has become even more depleted. And with a denser, gooier product left behind, refineries and terminals have mixed in additives to be able to work with it.

“Imagine you’re moving furniture on a floor and it doesn’t push really well,” said John Jechura, a chemical engineering professor at the Colorado School of Mines. “If you take a couple of small ball bearings and stick them under the furniture, now suddenly you’re rolling.”

Additives—proprietary chemicals or lighter hydrocarbons that would normally be further refined into diesel—are small molecules that disperse among the heavy hydrocarbons that make up the asphalt or No. 6 oil. They can also drive up the vapor pressure, leading to more emissions.

An infrared camera captures emissions coming from a heated tank owned by Sprague in Rhode Island. The company was found by the EPA to have violated the state’s air pollution regulations for failing to adequately limit emissions from asphalt and No. 6 tanks. Credit: EPA

Both asphalt and No. 6 fuel oil have been found to produce emissions of VOCs, though the emissions from No. 6 fuel oil appear to be greater.

When a team of experts studied emissions from heated tanks in Texas, they discovered one reason the estimates were flawed: The vapor pressure for asphalt and No. 6 fuel oil were nearly impossible to determine because the liquids were so thick. As a result, equations that estimated emissions by relying on vapor pressure—as the calculations used by most companies do—were at times off by several orders of magnitude, because they relied on assumed vapor pressure values that were far too low.

A Broken System

The unexpected emissions that Global Partners discovered were a symptom of a larger problem in how air quality is regulated. 

The EPA works hand-in-hand with state agencies to regulate pollutants from all sources. The EPA writes the regulations and, for the most part, the state agencies implement them.

“The whole giant [Clean Air Act] program, as complicated as it is, is designed to protect public health and the environment,” said Joro Walker, general counsel at Western Resource Advocates. “Because it’s so complicated, the public really relies on state and federal agencies, and sometimes their local air agencies, to understand and enforce those requirements, whether it’s in permitting or violations or whatever. We rely on those agencies to keep an eye on these facilities and make sure that they’re complying with the law.”

To do that, the regulators rely largely on estimated emissions based on complex equations that take into account specifics about the emissions source.

Since 1968, the EPA has published a handbook with guidance for estimating emissions called AP-42. Today, the reference document covers more than 200 different sources, including heated tanks. Contained within AP-42 are the values or other equations—called emissions factors—used to calculate how much a facility might emit. States grant permits based on those calculations, and companies then use the same process to estimate and report their annual emissions to the state.

For decades, the EPA also offered a free software program called TANKS, specifically for storage tanks, that states and companies could use to make the estimates.

The handbook is intended to help regulators assess the emissions in a region, not a specific location, and it was based on averages, not on specific sources of emissions. As a result, the EPA handbook specifically states that using the emissions factors to estimate emissions from any specific source, “is not recommended by EPA.” Yet, across the country, that is precisely how they are used. 

The handbook’s chapter on storage tanks—heated and otherwise—contains an additional disclaimer: The equations in the chapter were developed by the American Petroleum Institute, the largest U.S. trade association for the oil and gas industry. 

“It’s in the industry’s best interest to make sure these emissions factors are low,” said Ilan Levin, the associate director of Environmental Integrity Project, a nonprofit group that advocates for the enforcement of environmental laws, which has sued the EPA over its emissions factors in the past.

Kirsten Rosselot, a chemical engineer who worked on the analysis of vapor pressure and heated tank emissions, said, “The equations used to estimate the emissions from these tanks have never been validated. Estimates of emissions that are made using these equations don’t prove that emissions from heated tanks are below regulatory thresholds.”

In addition to the potentially flawed estimates that come from using the EPA handbook equations for specific sources, TANKS, the software the EPA gave to states to use, does not take into account the fact that asphalt and No. 6 fuel oil have to be heated above 100°F, which makes the products more volatile, according to regulators in Texas and sources within the industry.

And the default values the handbook recommended for No. 6 fuel oil—and which some states and companies use for asphalt, as well—were written before companies began using additives that have been found to produce higher vapor pressures.

Understanding Vapor Pressure and Emissions from Heated Storage Tanks

In 2020, the EPA updated the handbook’s equations for heated tanks, but it is still unclear whether they are accurate, Rosselot said, because of how challenging it is to find the actual vapor pressure of these products.

“Even if the equations that are used to estimate emissions work,” said Rosselot, “their result depends on the vapor pressure of the material being held, and there is at present no commercially available way to reliably measure the vapor pressure of the material being held in heated tanks.”

What Happened in Chelsea

The waterfront in Chelsea, Massachusetts, is littered with oil terminals and industrial polluters. But in the 1990s, there was one emissions source considered especially offensive to the city’s residents: asphalt. 

Roseann Bongiovanni, a lifelong resident of Chelsea, said she used to roll her windows up as she drove down Marginal Street, past some of the city’s massive asphalt tanks. “It was nauseating,” she said. And it was worse for people who lived next door.

“I don’t think I realized what asphalt is—I mean, isn’t that what’s on the ground?” said Bongiovanni, who got a crash course in that as she helped the city take on the tanks as an 18-year-old freshman at Boston University. Twenty-five years later, she is still fighting for clean air in Chelsea as the executive director of the nonprofit GreenRoots.

One of the tank farms in Chelsea was owned by Global Partners, the same company that owns tanks in South Portland. In 1997, Global Partners sought to convert some existing tanks used for other products to asphalt, and it was one straw too many for Chelsea residents. They teamed up with the city to fight back, arguing successfully that the noxious smells from living close to asphalt tanks amounted to a nuisance, which allowed the city’s board of health to ban new asphalt tanks from the city. 

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The board members knew from residents who lived near Global’s tanks that asphalt wasn’t the only problem, and they next took aim at No. 6 fuel oil. Ultimately, the board required Global Partners to install special equipment on its No. 6 tanks to help control the emissions.

Global opted to use a technology called carbon absorption canisters—equipment that could essentially filter out the pollutants and transfer them onto a solid surface.

“The carbon absorption canisters worked for a while, then failed and were replaced and failed again,” said Edmund Coletta, a spokesman for the Massachusetts Department of Environmental Quality. 

Global Partners’ Chelsea Terminal sits across the river from Boston and just steps away from a neighborhood. Credit: Julia Kane/Inside Climate News

When Global sampled its emissions to figure out what was going on, it discovered that the carbon was getting quickly saturated because the levels of emissions were much higher than  expected. They were so high that the tank farm should have been considered a “major source” of emissions, a designation that comes with heftier federal regulations and a requirement that companies use the best available technology to control their emissions.

In 2007, consultants working for Global Partners discovered that the company had received a shipment of No. 6 oil that, “while meeting all of the standard specifications for No. 6 oil, contained unexpectedly high levels” of benzene, toluene, ethylbenzene and xylene, hazardous chemicals which have a variety of health impacts.

But the company still did not know if the emissions it was measuring were from a bad batch of No. 6 fuel oil or if they represented a larger issue. According to Global’s letter to the EPA, the consultants analyzed samples of No. 6 from “other available sources supplying the region” and found that the basic composition of the product they were receiving was fundamentally different from what it was in the past. 

Those changes were resulting in VOC emission levels substantially higher than those predicted by AP-42 calculations,” Global’s attorney wrote

The company’s unexpected findings raised red flags with both state and federal environmental agencies. The EPA’s New England office began inquiries across the region soon after, and Global began working with state regulators to find and implement an approved method for dealing with its emissions problem in Chelsea.

Ultimately, Global Partners was able to install equipment to mitigate its emissions on its Chelsea tanks, and avoid the financial burden of being classified as a major source of emissions. But no definitive health study was conducted to determine whether the emissions from the tanks might have harmed nearby residents.

But outside of Chelsea, companies that owned heated tanks, including Global Partners, were still operating without emissions controls and underreporting their emissions. 

An Investigation and Two Settlements

In 2010, in the wake of Global Partners’ discovery in Chelsea, the EPA’s New England office sent letters to seven companies in the region asking questions about their heated tanks and informing them that the EPA was investigating whether the companies had violated the Clean Air Act. 

Two companies, Gulf and Motiva, responded that they did not own any heated tanks. 

But Global Partners and Sprague, which did own heated tanks, were asked by the federal agency to measure the actual emissions from the tanks. 

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The findings were surprising. At Sprague’s terminal in Searsport, Maine, emissions testing on one of the company’s No. 6 fuel oil tanks discovered emissions that were 500 times what the company had been reporting

The emissions were still below a federal pollution threshold that would have required additional regulation. But the violations underscored what had been found in Chelsea: Chemicals that could have an impact on public health were being emitted without mitigation or acknowledgement by the company or the regulators.

Both companies contested the method the EPA required for sampling their tank emissions, saying it falsely inflated the emissions, but the EPA stood by its methodology. 

“To my knowledge, this is the only time that emissions from heated tanks were directly measured and made publicly available,” said Rosselot. And the measurements in Maine, she said, may provide the only existing data about what the heated tanks that store asphalt and No. 6 fuel oil across the country are emitting.

Elizabeth Hernberg, Sprague’s then-managing director for health, safety and environment, wrote in a 2012 letter to the EPA, “The science of estimating #6 oil emissions has up until now been a theoretical approach.” Because of the actions of the EPA’s New England office, she wrote, “the bulk storage industry is becoming aware of the inconsistencies with TANKS and the #6 oil operating conditions, and like Sprague, is eager to find a better approach at estimating emissions … The industry nationally faces the same dilemma, with potentially much greater significance at the much larger facilities in other parts of the country.”

The results were similar at Global Partners’ terminal in South Portland, where the EPA-ordered testing revealed that the potential emissions from the No. 6 fuel oil and asphalt operations there alone exceeded 40 tons per year, violating the Clean Air Act and putting the terminal over the threshold for being a major source of emissions that would fall under stricter regulations. 

A cyclist passes Sprague's Everett terminal, located across the street from a group of homes. Credit: Julia Kane/Inside Climate News
A cyclist passes Sprague’s Everett terminal, located across the street from a group of homes. Credit: Julia Kane/Inside Climate News

Both Global and Sprague also had been asked by the EPA to hire labs to determine the actual vapor pressure of their products. The sample of No. 6 fuel oil sent to the laboratory by Sprague was found to have a vapor pressure of 0.0083 psi—200 times higher than the default value the petroleum industry included in the EPA handbook at the time and four times higher than an updated figure the manual now includes. Because of the direct relationship between vapor pressure and emissions, this was further evidence that the method being used to estimate emissions was inherently flawed.

As the EPA continued its investigation, Maine’s state environmental agency, in charge of regulating the facilities, did little in response to the federal agency’s inquiry. In an October 2015 letter, Susan Studlien, then-director of the office of environmental stewardship at the EPA’s New England field office, wrote to the state’s then-director of the bureau of air quality to express her concern about amendments to Sprague’s permit that had been approved by the state agency.

“I write to inform you of EPA’s view that the license amendments (of which EPA was unaware until after their issuance) fail to correct the underlying violations cited in the NOVs,” she wrote, referring to the citations or “notices of violation” the company had received. The company, Studlien wrote, should be using emissions controls on its heated tanks across New England. 

The EPA Investigate Heated Tanks Throughout New England

In her letter, Studlien said she was concerned that the state environmental department was not considering known technology fixes to reduce emissions, specifically, the technology used by Global Partners on its tanks in Chelsea. But since the EPA did not require companies to install such technology, the agency could not force the companies to make the change.

As the years passed, a new complication arose, according to Braczyk, from the Massachusetts DEP, who was collaborating with the EPA. “When the Trump administration came in, a lot of things just kind of froze,” he said.

Processes that typically took weeks or a month took a year instead. “Everything had to get reviewed through the Department of Justice,” Braczyk said. “And that’s where everything kind of stalled.”

In 2019, nearly a decade after beginning its investigation, the EPA announced a proposed legal settlement with Global Partners. The agency cited Global for Clean Air Act violations at its facility near the Liscords’ home. According to the EPA, the company’s asphalt and No. 6 fuel oil operations could have been emitting twice the level of VOCs that its permit allowed, a problem that the EPA said went back about a decade.

Global Partners agreed that it would restrict how often its heated tanks ran and how much product they carried, that it would add control technology to reduce the emissions and pay $190,000 in fines.

“We strive to be good neighbors in all the communities we operate while we deliver the essential energy and products that families, businesses, and economies need for daily life,” said Liz Fuller, a spokeswoman for Global Partners. “Safety is the top priority and we operate our facilities under strict oversight from federal and state regulators.

On May 29, 2020, the EPA and the state of Massachusetts announced a legal settlement with Sprague over its asphalt and No. 6 operations in Searsport and South Portland, Maine; Newington, New Hampshire; Everett and Quincy, Massachusetts; and Providence, Rhode Island. The company was cited for violating the federally enforced state requirements for VOCs, and ordered to limit how many heated tanks it could operate and how much product could be processed at each facility, to keep the company within its operating permit limits. 

“The Consent Decree is now finalized, and subject to coming to a consensus with the town and DEP, we will obtain any necessary permits, construct the approved solution, and build a timeline for implementation,” said Shana Hoch, Sprague’s Managing Director, Marketing & Customer Experience.

A Half-Hearted Pursuit

As EPA’s New England office investigated emissions at tank terminals around the region, the office provided updates to the federal agency’s headquarters in Washington, according to Dave Deegan, a spokesman for the regional office. But it is unclear how far the EPA has pursued the issue in other parts of the country. 

In response to questions, an EPA spokeswoman said that, in addition to the investigation of Global and Sprague in New England, it has in progress “initial investigations of other sources.” The spokeswoman did not elaborate on where those cases were, but Freedom of Information Act requests filed with the agency indicated that only two of the nine other EPA regional offices had taken any actions related to heated tanks.

In July 2019, inspectors in the Great Lakes regional office made an unannounced inspection at the Waterfront Petroleum Terminal in Detroit, which had four heated tanks containing asphalt and five tanks containing No. 6 fuel oil. Using an infrared camera, inspectors observed unexpected levels of VOCs being emitted from the vents of one asphalt tank and one No. 6 fuel oil tank. A spokesman for the regional office did not respond to questions about whether the agency took any punitive action, or if the investigation was ongoing. 

In EPA’s south central region, investigators requested information from and visited the Houston Fuel Oil Terminal in 2015, which owned 128 tanks along the Houston Ship Channel, some of which contained No. 6 fuel oil. The investigators found elevated levels of VOCs coming from the tanks. “We would not expect to see VOC emissions coming from a tank containing low vapor pressure liquids that is not in the process of filling,” inspectors wrote in a 2015 report. More than five years later, according to the EPA, the investigation is ongoing.

In November 2020, after the legal settlements with Global Partners and Sprague, the EPA published an enforcement alert titled “EPA Reminder About Inappropriate Use of AP-42 Emissions Factors,” acknowledging what the agency had found in Maine and other states in its New England region.

In a four page memo, the EPA reiterated its warning that the standard method for estimating heated tanks emissions—the petroleum industry’s equations included in the EPA manual—should not be used for specific sites. 

The emissions and vapor pressure testing conducted in Maine in 2012 and 2013, the agency wrote, “suggested that in those cases the use of the default vapor pressure in [the manual] had resulted in emissions estimates that were understated by a factor of 100 for permitting and reporting purposes.”

The memo went on to recommend a series of steps a company could take to ensure accurate emissions reporting, including continuous emissions monitoring and the use of infrared cameras. In a list descending from most to least accurate, the petroleum industry emissions estimation method in the manual was at the bottom. 

“Remember, AP-42 emission factors should only be used as a last resort,” the memo said in bold font, referring to the EPA manual, adding, “Even then the facility assumes all risk associated with their use!”

But the EPA still did not ban the use of the estimation method, and, not surprisingly, given the costs of direct testing and measurement, companies—and most states—have continued to use it.

A Patchwork of Regulations

When Inside Climate News surveyed regulators from air quality agencies in all 50 states, a majority said that they relied on the industry equations included in the manual for estimating emissions and did not use direct, site-specific measurements. Many also said they used the EPA TANKS program to calculate emissions from tanks containing asphalt or No. 6 fuel oil, a method that cannot accurately estimate heated tank emissions.

In Arkansas, for instance, the communications manager for the state Department of Energy and Environment said they used the TANKS program because it “accounts for heated tanks.” But even the EPA—the creator of TANKS—has said that the program does not provide accurate estimates. The federal agency stopped updating the software in 2014, after finding that it was flawed.

Some states, like Connecticut, said that they did not even keep track of where tanks containing asphalt and No. 6 fuel were located, because they assumed the emissions were negligible. “We have very little information on where a No. 6 oil tank would be located, because historically, the emissions were presumed to be so low as to not trigger any of our registration or permitting processes, which would cause us to follow or track their emissions,” said Jaimeson Sinclair, the director of the Connecticut Department of Energy and Environmental Protection’s engineering section.

And while technology exists that could reduce the emission of VOCs—perhaps by as much as 99 percent—a recent review by the state of Maine found “the majority of tanks of this type being operated in the United States do not utilize any type of add-on control equipment to reduce emissions.” 

In a few states, though, regulators have taken a keen interest in heated storage tanks.

In Texas, for example, state regulators in the early 2000s launched investigations into what’s known as the emissions gap—the difference between the amount of VOCs they expected based on known sources and the amount they found when they sampled the air. That allowed the regulators to pinpoint problems—flaring, for instance—and try to close the gap. But even after resolving those problems, a gap remained.

The Texas regulators suspected a possible reason for the discrepancy: The faulty assumptions about heated tanks and the vapor pressure of their products. They hired a team of researchers from the University of Texas, including Rosselot, to study the issue and in studies published in 2014 and 2015, they affirmed that emissions from heated tanks were almost certainly being undercounted and that the tanks were likely contributing to the emissions gap.

How No. 6 Fuel Oil and Asphalt are Produced and Stored

Russ Nettles, a technical specialist with the Texas Commission on Environmental Quality, took particular interest in the issue. Nettles, who died in 2017, began sounding an alarm about emissions from heated tanks at EPA conferences and in national industry workshops held in Texas. Emissions from heated tanks were being under-counted, he said, and the tools being used to estimate them—the petroleum industry equations in the EPA manual and the TANKS program—were wrong.

Nettles’ efforts resulted in some changes in Texas, including the state dropping the use of the TANKS program, and stressing that companies should test for the true vapor pressure of their products rather than using default values, when possible. But the guidance echoed that of the EPA in saying that, when site-specific monitoring was not available, companies could use the petroleum industry equations in the agency’s manual to estimate emissions instead.

Asked about the continued use of the petroleum industry formula in most states, the EPA spokeswoman said, “We would recommend that States consider requiring testing to obtain more accurate emissions factors, given that the Sprague and Global matters suggest the emission factors are not accurate.”

Is Our Health at Risk?

With few actual measurements of what is being emitted from the tanks, residents who live near heated tanks, like the Liscords in communities like South Portland, are left wondering whether it is safe to breathe the air around them.

“People who live, work and play downwind of heated tanks holding heavy refinery liquids are right to be concerned about the potential health effects of their exposure to the emissions from these tanks,” said Rosselot, who was among the team of experts who studied heated tank emissions in Texas at the request of state regulators. 

While it has long been known that volatile organic chemicals like benzene and toluene in significant amounts can have serious health impacts, virtually no research exists on the possible effects on human health of the VOCs emitted by heated tanks, and the few studies that have been conducted have not been without controversy.

In 2007, for example, the Agency for Toxic Substances and Disease Registry (ATSDR) issued a report on health risks from asphalt emissions in response to years of complaints from communities across the country that were exposed to asphalt fumes. 

The agency’s investigations primarily focused on asphalt plants in Arizona, California, Georgia, New York, North Carolina and Utah in the years from 1998 to 2004, but in one location—Salisbury, North Carolina—the researchers looked at a tank farm. The terminal in Salisbury had been a source of hundreds of odor complaints from 1997 to 2001 from residents living near the tank farm and an asphalt plant, and the state and county health agencies cited a high incidence of serious health problems in nearby residents and workers. 

The agency investigators evaluated samples of tank emissions taken over the course of four months six years earlier, in 2001. The study’s authors found that the chemicals contained in asphalt emissions from the tank did not exceed federal safety levels and did not pose a threat to public health. But the investigation was conducted after Associated Asphalt, the company that owned the tanks, had already installed technology to mitigate emissions.

Given the limited nature of the samples and the fact that the company had taken steps to control emissions, the study’s findings did not instill much confidence in residents there.

No other direct study of the effect of emissions from heated asphalt tanks could be located, but a handful of studies from federal agencies have looked at how workers who were exposed to asphalt fumes through their jobs were affected. The Occupational Safety and Health Administration lists headache, skin rash, sensitization, fatigue, reduced appetite, throat and eye irritation, cough and skin cancer as symptoms of asphalt exposure on its website. 

When the federal Centers for Disease Control and Prevention looked into occupational exposure to asphalt in 2000, the study’s authors found that complaints of eye, nose and throat irritation were common among workers who performed different kinds of jobs using asphalt, including road paving, shingle manufacturing and work at hot-mix plants and terminals. Some workers also reported skin irritation, nausea, headaches and fatigue. These reactions were found in workers whose exposure was below OSHA’s allowable limits. Some studies indicated elevated rates of lung, bladder, kidney, brain and liver cancer among workers, but the researchers were unable to draw a direct causal relationship.

The asphalt plant workers in the study were likely to have been exposed to higher levels of fumes than people who live near heated asphalt tanks. But the workers also went home at the end of the day, while for residents who live near tanks the fumes are constant. 

A subset of VOCs called Hazardous Air Pollutants, or HAPs have been linked with symptoms like headaches and breathing problems in the short-term, and some cancers and neurological problems in the long-term. 

Exposure to high levels of the HAP benzene, for example, has been linked to acute myeloid leukemia, and women who were exposed to high levels for an extended period had irregular menstrual periods and decreased ovary size. An acute exposure to benzene at very high levels can be fatal.

“Benzene is a known carcinogen, thus there is no safe dose,” said Joan Casey, an environmental epidemiologist at the Columbia Mailman School of Public Health.

But different states have different bars for what exposure level is considered acceptable.

The Maine Center for Disease Control and Prevention sets the bar for benzene at 0.4 parts per billion. At that level of ambient exposure, there is an incremental lifetime cancer risk of 1-in-100,000 over what would normally occur in the general population, according to the state. In Massachusetts, the allowable ambient exposure limit is much lower—0.03 parts per billion—a level associated with an incremental lifetime cancer risk of 1-in-1,000,000. 

In South Portland, Unsettled Questions

The Liscords considered buying a few different houses before they landed on the white, craftsman style home on Reynolds Street in South Portland. It felt just right: It had an ideal layout, it would be easy to make energy-efficient and it was on a street with friendly neighbors, who said it was a good place to raise kids. 

But that was before they knew about the smell. Once they moved in, it was unavoidable on many days. When the EPA’s settlement with Global Partners—and later, with Sprague—was announced, their fears only grew.

The idea that Global’s tank emissions were so high in a place surrounded by tightly-knit neighborhoods came as a shock. That the EPA had been investigating this for nearly a decade without notifying residents only deepened the concern. 

Rob and Brittany Liscord walk with their dog, Arlo, along the Greenbelt Walkway in their neighborhood in South Portland, Maine on Feb. 13. The Liscords live one tenth of a mile from storage tanks (in the background) owned by Global Partners, an energy company that uses its tanks to store petroleum products. Rob Liscord said he sometimes gets headaches after running and both have worried how the air quality in their neighborhood is affecting their health. Credit: Yoon S. Byun
Rob and Brittany Liscord walk with their dog, Arlo, along the Greenbelt Walkway in their neighborhood in South Portland, Maine on Feb. 13. The Liscords live one tenth of a mile from storage tanks (in the background) owned by Global Partners, an energy company that uses its tanks to store petroleum products. Rob Liscord said he sometimes gets headaches after running and both have worried how the air quality in their neighborhood is affecting their health. Credit: Yoon S. Byun

And though the EPA had determined what was being emitted by the tanks, it did not study how those emissions might be affecting people who lived or worked or went to school near them. That work was left up to the state.

The Maine Department of Environmental Protection has had a network of monitors studying the air near the South Portland tanks since November 2019, and has found levels of naphthalene—a VOC that can cause respiratory and neurological problems—2.5 times the ambient exposure limit set by the state. But residents say the monitors are too far from the tanks to truly reflect what is coming from them, and the state appears to agree—after more than a year of monitoring, it has plans to move four of the monitors closer to the tanks.

There is reason to believe those monitors will find higher levels of VOCs. After the agreement between the EPA and Global Partners was announced in 2019, the state supplied air canisters to volunteers in South Portland, who took samples of the air that were then analyzed in a state lab. Though not a rigorous scientific study, the grab samples taken outside homes near the tanks found spikes of benzene as high as 5.8 and 8 times the state’s ambient air guidelines.

When Maine’s state toxicologist, Andy Smith, presented the initial findings at a City Council meeting in December 2019, he noted that the spikes found in the citizen-led samples did not rise above the acute risk threshold for the state, meaning that a short exposure at that level would not be expected to have health impacts.

The International Liquid Terminals Association, the trade association for tank terminals, has downplayed the findings in the grab samples. “It’s unlikely that the storage tanks at terminals are a significant source of naphthalene emissions,” said spokeswoman Cathy Landry. “Most airborne emissions of naphthalene result from the combustion (not storage) of petroleum products.” She also pointed to a statement from Maine regulators indicating that it’s not appropriate to use grab sample data to extrapolate about longer term levels.

Residents like the Liscords, though, worried that the spikes found in the citizen-led samples represented what they were breathing all day, every day. 

Daycare owners Gina Kostopoulos and Annmarie Marshall were concerned that the emissions might explain the headaches staff workers complained about on days when the air was thick with petroleum smells. And across a small cove from Global’s tanks, Barbara Saulle wondered whether the fumes that regularly filled her home could have caused her miscarriages, her migraines or two sons’ inexplicable liver disorders. 

In community meetings over the last year and a half—held in person or, and more recently, virtually—residents have pressured state regulators to require more monitoring, including 24/7 fenceline monitoring around the emissions sources and the use of more technology to control the emissions.

South Portland residents said that, as a result of the settlements with both companies, they have some reasons to celebrate, including the pending installation of emissions control technology at Global Partners and Sprague facilities, new state recommendations related to the use of infrared cameras to detect vapor leaks and emissions testing for new and modified heated tanks.

But unlike Massachusetts, which now bans the use of the petroleum industry equations in estimating storage tank emissions, Maine continues to allow it. A recent state report recommended against the use of continuous monitoring at the tanks or monitoring along the perimeter of the facilities, also known as fenceline monitoring.

The Liscords say they want to stay in their home in South Portland, but as they think about having kids, they’re not sure it’s safe for them to stay there. They’re not sure they can go, either.

“If we move, someone else is going to live in this house,” said Brittany Liscord. “The reality is, people still live here.”

Madeleine Kornfeld contributed reporting. Top video credit: Jeremy Weir